Generally, a relatively low current consumption is required in a mobile semiconductor memory device, as compared with a main memory device or a graphic memory device. Therefore, a standby current consumption is a critical factor in the mobile memory device.
Recently, a memory device achieves a fast response speed by reducing gate pitch of a transistor and then reducing a threshold voltage of the transistor. However, the reduced threshold voltage of the transistor may cause a problem of increasing off-current in a standby mode. Particularly, in the case of a transistor to which a high voltage VPP is applied, the off-current is more increased inevitably.
In the case of the mobile memory device, an approach for reducing off-current by using a long channel transistor to which a high voltage is applied can be used. However, there is a limit to the off current reduction in such approach.